Moreno-Sánchez R, Devars S, López-Gómez F, Uribe A, Corona N
Departamento de Bioquímica, Instituto Nacional de Cardiología, México, D.F.
Biochim Biophys Acta. 1991 Nov 7;1060(3):284-92. doi: 10.1016/s0005-2728(05)80318-4.
The flux control distribution of the net rate of state 3 respiration was determined in heart and kidney mitochondria incubated with low concentrations of pyruvate (0.5 mM) or 2-oxoglutarate (1 mM), and in conditions that led to activation of NAD-linked dehydrogenases, i.e., high substrate or Ca2+ concentrations. Control of flux was exerted by the ATP/ADP carrier (flux control coefficient, ci = 0.37) and Site 1 of the respiratory chain (ci = 0.28) when dehydrogenase activity was low. Control of the process shifted to the ATP synthase (ci = 0.32) and the Pi carrier (Ci = 0.27) when dehydrogenases were activated by high pyruvate and high Ca2+. The changes in the control exerted by the ATP/ADP carrier and the ATP synthase were not due to changes in the transmembrane potential, nor to a modification of intramitochondrial ATP/ADP ratios. Applying the summation theorem of the control analysis, it was found that at low Ca2+ and pyruvate concentrations the dehydrogenases shared the control of state 3 respiration with other steps. The NAD-linked dehydrogenases did not exert any significant control at high Ca2+ or high pyruvate concentrations.
在低浓度丙酮酸（0.5 mM）或2-氧代戊二酸（1 mM）孵育的心脏和肾脏线粒体中，以及在导致NAD连接脱氢酶激活的条件下，即高底物或Ca2+浓度下，测定了状态3呼吸净速率的通量控制分布。当脱氢酶活性较低时，通量控制由ATP/ADP载体（通量控制系数，ci = 0.37）和呼吸链的位点1（ci = 0.28）施加。当脱氢酶被高丙酮酸和高Ca2+激活时，该过程的控制转移到ATP合酶（ci = 0.32）和磷酸载体（Ci = 0.27）。ATP/ADP载体和ATP合酶施加的控制变化不是由于跨膜电位的变化，也不是由于线粒体内ATP/ADP比率的改变。应用控制分析的求和定理，发现在低Ca2+和丙酮酸浓度下，脱氢酶与其他步骤共同控制状态3呼吸。在高Ca2+或高丙酮酸浓度下，NAD连接脱氢酶没有发挥任何显著的控制作用。
